From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752735AbdGMX3b (ORCPT ); Thu, 13 Jul 2017 19:29:31 -0400 Received: from mx0a-001b2d01.pphosted.com ([148.163.156.1]:45937 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751375AbdGMX32 (ORCPT ); Thu, 13 Jul 2017 19:29:28 -0400 Date: Thu, 13 Jul 2017 16:29:16 -0700 From: Ram Pai To: Balbir Singh Cc: "open list:LINUX FOR POWERPC (32-BIT AND 64-BIT)" , "linux-kernel@vger.kernel.org" , linux-arch , linux-mm , "maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT)" , "open list:DOCUMENTATION" , linux-kselftest@vger.kernel.org, Benjamin Herrenschmidt , Paul Mackerras , Michael Ellerman , Anshuman Khandual , Aneesh Kumar KV , Dave Hansen , Haren Myneni/Beaverton/IBM , Arnd Bergmann , "akpm@linux-foundation.org" , Jonathan Corbet , Ingo Molnar Subject: Re: [RFC v5 15/38] powerpc: helper function to read,write AMR,IAMR,UAMOR registers Reply-To: Ram Pai References: <1499289735-14220-1-git-send-email-linuxram@us.ibm.com> <1499289735-14220-16-git-send-email-linuxram@us.ibm.com> <20170712152601.3b2f52ed@firefly.ozlabs.ibm.com> <20170713075502.GG5525@ram.oc3035372033.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.20 (2009-12-10) X-TM-AS-GCONF: 00 x-cbid: 17071323-0036-0000-0000-00000248BB5F X-IBM-SpamModules-Scores: X-IBM-SpamModules-Versions: BY=3.00007363; HX=3.00000241; KW=3.00000007; PH=3.00000004; SC=3.00000214; SDB=6.00887178; UDB=6.00442925; IPR=6.00667318; BA=6.00005470; NDR=6.00000001; ZLA=6.00000005; ZF=6.00000009; ZB=6.00000000; ZP=6.00000000; ZH=6.00000000; ZU=6.00000002; MB=3.00016218; XFM=3.00000015; UTC=2017-07-13 23:29:25 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 17071323-0037-0000-0000-000041164143 Message-Id: <20170713232916.GK5525@ram.oc3035372033.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:,, definitions=2017-07-13_12:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 spamscore=0 suspectscore=0 malwarescore=0 phishscore=0 adultscore=0 bulkscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1706020000 definitions=main-1707130363 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Jul 13, 2017 at 07:49:05PM +1000, Balbir Singh wrote: > On Thu, Jul 13, 2017 at 5:55 PM, Ram Pai wrote: > > On Wed, Jul 12, 2017 at 03:26:01PM +1000, Balbir Singh wrote: > >> On Wed, 5 Jul 2017 14:21:52 -0700 > >> Ram Pai wrote: > >> > >> > Implements helper functions to read and write the key related > >> > registers; AMR, IAMR, UAMOR. > >> > > >> > AMR register tracks the read,write permission of a key > >> > IAMR register tracks the execute permission of a key > >> > UAMOR register enables and disables a key > >> > > >> > Signed-off-by: Ram Pai > >> > --- > >> > arch/powerpc/include/asm/book3s/64/pgtable.h | 60 ++++++++++++++++++++++++++ > >> > 1 files changed, 60 insertions(+), 0 deletions(-) > >> > > >> > diff --git a/arch/powerpc/include/asm/book3s/64/pgtable.h b/arch/powerpc/include/asm/book3s/64/pgtable.h > >> > index 85bc987..435d6a7 100644 > >> > --- a/arch/powerpc/include/asm/book3s/64/pgtable.h > >> > +++ b/arch/powerpc/include/asm/book3s/64/pgtable.h > >> > @@ -428,6 +428,66 @@ static inline void huge_ptep_set_wrprotect(struct mm_struct *mm, > >> > pte_update(mm, addr, ptep, 0, _PAGE_PRIVILEGED, 1); > >> > } > >> > > >> > +#ifdef CONFIG_PPC64_MEMORY_PROTECTION_KEYS > >> > + > >> > +#include > >> > +static inline u64 read_amr(void) > >> > +{ > >> > + return mfspr(SPRN_AMR); > >> > +} > >> > +static inline void write_amr(u64 value) > >> > +{ > >> > + mtspr(SPRN_AMR, value); > >> > +} > >> > +static inline u64 read_iamr(void) > >> > +{ > >> > + return mfspr(SPRN_IAMR); > >> > +} > >> > +static inline void write_iamr(u64 value) > >> > +{ > >> > + mtspr(SPRN_IAMR, value); > >> > +} > >> > +static inline u64 read_uamor(void) > >> > +{ > >> > + return mfspr(SPRN_UAMOR); > >> > +} > >> > +static inline void write_uamor(u64 value) > >> > +{ > >> > + mtspr(SPRN_UAMOR, value); > >> > +} > >> > + > >> > +#else /* CONFIG_PPC64_MEMORY_PROTECTION_KEYS */ > >> > + > >> > +static inline u64 read_amr(void) > >> > +{ > >> > + WARN(1, "%s called with MEMORY PROTECTION KEYS disabled\n", __func__); > >> > + return -1; > >> > +} > >> > >> Why do we need to have a version here if we are going to WARN(), why not > >> let the compilation fail if called from outside of CONFIG_PPC64_MEMORY_PROTECTION_KEYS? > >> Is that the intention? > > > > I did not want to stop someone; kernel module for example, from calling > > these interfaces from outside the pkey domain. > > > > Either way can be argued to be correct, I suppose. > > Nope, build failures are better than run time failures, otherwise the > kernel will split its guts warning and warning here. > Well these are helper functions that can be called by anyone under any situation. I will rather have them defined unconditionally; under no ifdefs. No spewing of warnings anymore. The registers will be read or written as told. It just makes sense that way. RP -- Ram Pai